import io

import boto3
import pytest
from moto import mock_aws

from streamstack.core.s3 import S3SeekableFile, open_s3_buffered

BUCKET = "test-bucket"
KEY = "test/video.mp4"
CONTENT = b"Hello World! This is seekable S3 content for testing purposes."


@pytest.fixture
def s3_object():
    with mock_aws():
        s3 = boto3.client("s3", region_name="us-east-1")
        s3.create_bucket(Bucket=BUCKET)
        s3.put_object(Bucket=BUCKET, Key=KEY, Body=CONTENT)
        yield s3


def test_readable_and_seekable(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    assert f.readable() is True
    assert f.seekable() is True


def test_size(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    assert f.size == len(CONTENT)


def test_initial_position(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    assert f.tell() == 0


def test_read_from_start(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    data = f.read(5)
    assert data == CONTENT[:5]
    assert f.tell() == 5


def test_seek_set(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    pos = f.seek(7)
    assert pos == 7
    assert f.tell() == 7
    data = f.read(5)
    assert data == CONTENT[7:12]


def test_seek_cur(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    f.read(5)
    f.seek(2, io.SEEK_CUR)
    assert f.tell() == 7


def test_seek_end(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    pos = f.seek(-5, io.SEEK_END)
    assert pos == len(CONTENT) - 5
    data = f.read()
    assert data == CONTENT[-5:]


def test_seek_beyond_end_clamps(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    pos = f.seek(len(CONTENT) + 100)
    assert pos == len(CONTENT)


def test_read_at_eof_returns_empty(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    f.seek(0, io.SEEK_END)
    buf = bytearray(10)
    n = f.readinto(buf)
    assert n == 0


def test_full_read(s3_object):
    f = S3SeekableFile(BUCKET, KEY, s3_client=s3_object)
    data = f.read()
    assert data == CONTENT


def test_open_s3_buffered(s3_object):
    with mock_aws():
        s3 = boto3.client("s3", region_name="us-east-1")
        s3.create_bucket(Bucket=BUCKET)
        s3.put_object(Bucket=BUCKET, Key=KEY, Body=CONTENT)
        with patch_s3_client(s3):
            buf = open_s3_buffered(BUCKET, KEY)
            assert isinstance(buf, io.BufferedReader)
            data = buf.read(5)
            assert data == CONTENT[:5]


def patch_s3_client(client):
    from unittest.mock import patch

    return patch("streamstack.core.s3.get_s3_client", return_value=client)